Prior to the twentieth century, wax seals were employed to personalize a document, and provide an indication of the document's origin and authenticity. Today, similar physical seals are still used by notaries as proof that a signature was officially witnessed, but otherwise a seal is primarily used as a symbolic or ceremonial decoration. Given the ease of replicating a seal using modern equipment, seals are no longer useful for verifying authorship or authenticity of a document. In the digital world, certificates and encryption keys have, in some ways, taken the place of seals to provide security and/or authenticity for digital documents, pages, programs, and other types of digital media. However, traditional digital certificates and encryption keys are not useable for securing printed documents.